It is already known to use transformers for the wireless transmission of energy and data between the vehicle body and a removable part, e.g., a vehicle seat. To that end, inductive transformers are used in particular, windings at the primary side and at the secondary side being located in each case on an iron core. The core halves lie flat against each other. Due to the air gap, in order to avoid iron losses, an appropriate core material is used, for example, that is known under the trade name SOMALLOY, which is made of 95% iron powder and is bound into plastic polyamide.